1. Field of the Invention
The present invention relates to a portable power cutter comprising a prime mover such as a small air-cooled two-cycle gasoline engine or an electric motor. More particularly, the invention relates to a power cutter comprising a dust suction-discharge fan for discharging by sucking dust resulting from cutting operations with cutting means such as a cutter blade.
2. The Prior Art
In portable power cutters of this type, there has heretofore been proposed and used a body or frame carrying a prime mover, an operative cutting component attached to the frame and including cutting means such as a cutter blade, a safety cover, etc., and a dust suction-discharge fan mounted on the operative cutting component for discharging by sucking dust resulting from cutting operations on a concrete-formed material or the like.
In such conventional portable power cutters, the cutting means is driven to rotate by the prime mover via a belt-type driving mechanism. The driving force of the prime mover is also transmitted to the dust suction-discharge fan via another belt-type mechanism to rotationally drive the dust suction-discharge fan.
In the conventional power cutters, however, the direction of the dust discharge port of the dust suction-discharge fan is not changeable, and thus the dust discharge direction is fixed. Accordingly, there are problems in certain operational conditions or operational positions that dust discharge from the fan is likely to strike the operator, and that a dust collecting bag, a pipe or hose or the like, which is connected to the discharge port, can be an obstacle to operation.
Further, in the conventional power cutter, when the cutting means is driven to rotate, the dust suction-discharge fan is also inevitably driven to rotate. Accordingly, there is a problem that even in cutting operations which require a strong driving force for cutting and from which significant levels of dust do not result, as, for example, in the cutting of an iron pipe, the dust suction-discharge fan is nevertheless ceaselessly driven to rotate, leading to waste of power of the prime mover.